This application claims the benefit of Korean Patent Application No. 4407/1997, filed in Korea on Feb. 14, 1997, which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a serial data transmission apparatus, and more particularly, to an improved serial data transmission apparatus which is capable of enhancing operational speed and is well adapted for serial data transmission using a cyclic redundancy checking (CRC) method. Although the present invention is suitable for a wide scope of applications, it is particularly suitable for serially transmitting a large amount of data. The present invention also relates to a corresponding method for serially transmitting data.
2. Discussion of Related Art
FIG. 1 illustrates a conventional serial data transmission apparatus. As shown therein, the conventional serial data transmission apparatus includes a transceiver 10 and a receiver 20.
The transceiver 10 includes a data storing unit 11 for storing source data to be transmitted and a data checking unit 12 for checking the data from the data storing unit 11 based on a cyclic redundancy checking (CRC) method. The transceiver 10 also includes a data combining unit 13 for combining the outputs from the data storing unit 11 and the data checking unit 12 to generate new data. The transceiver 10 further includes a data encoding unit 14 for encoding the data output from the data combining unit 13 using a non-return-zero-inverted (NRZI) method and serially transmitting the encoded data via a channel.
The receiver 20 includes a data decoding unit 21 for receiving and decoding the NRZI type data transmitted from the transceiver 10 and a data separation unit 22 for separating the data from the data decoding unit 21 to restore it to the form before the data combination by the transceiver 10. Also, the receiver 20 includes a data storing unit 23 for temporarily storing the source data separated by the data separation unit 22, a data checking unit 24 for checking the output from the data storing unit 23 based on the CRC method, and a data comparison unit 25 for comparing the data in order to judge whether the output from the data checking unit 24 and the detection data separated by the data separation unit 22 are identical.
The operation of the conventional serial data transmission apparatus will now be explained with reference to the accompanying drawings.
First, the data storing unit 11 of the transceiver 10 outputs source data D1 to the data checking unit 12. Then, the data checking unit 12 checks the data D1 based on the CRC method and outputs the detection data d1.
Here, the data D1 through Dn are outputted from the data storing unit 11 in a packet-format. In addition, the cyclic redundancy checking (CRC) method employed in the data checking unit 12 is a method of checking whether the data is transmitted without an error. This is accomplished by dividing a k-bit binary data M by an (n+1)-bit data P to produce an n-bit residual F and attaching the n-bit residual F to the front of the k-bit binary data M when transmitting the k-bit binary data M. Then, the combined (n+k)-bit data is output to the next circuit block which checks whether a residual is produced when the (n+k)-bit combined data is divided by the (n+1)-bit data P. If no residual is produced by the division, the transmission of the k-bit data M is judged to have been performed without an error.
In addition, the data combining unit 13 combines the data D1 from the data storing unit 11 and the detection data d1 from the data checking unit 12, and generates a new data (D1+d1). The data (D1+d1) is not to be confused as a mathematical sum of the data D1 and d1. Instead, the data (D1+d1) is generated by combining the bits of the data D1 and d1, i.e., attaching the data d1 to the end of the data D1 as shown in FIG. 2. The data combining unit 13, as shown in FIG. 2, changes the data D1 and d1 having different lengths A and B, respectively, into a new (A+B)-bit data (D1+d1).
The data encoding unit 14 encodes the data (D1+d1) by the non-return-to-zero-inverted (NRZI) method. The encoded data (D1+d1)xe2x80x2 is transmitted to the receiver 20.
As shown in FIG. 3, the non-return-to-zero-inverted (NRZI) method is a data encoding method for changing the magnetized state of the encoded data only at falling edges, i.e., when the source data changes the state from 1 to 0, thus generating a different type of data. The method may also be set to change the magnetized state of the encoded data only at rising edges.
In addition, the data decoding unit 21 of the receiver 20 decodes the transmitted data (D1+d1)xe2x80x2 to restore the original form of the data (D1+d1) and outputs the data to the data separation unit 22. The data separation unit 22 separates the data (D1+d1) into the source data D1 and the detection data d1, and outputs the separated data D1 and d1.
The source data D1 separated by the data separation unit 22 is transmitted to the data checking unit 24 through the data storing unit 23. The data checking unit 24 checks the source data D1 based on the CRC method and outputs a different detection data d1xe2x80x2.
The data comparison unit 25 decides whether the detection data d1xe2x80x2 output by the data checking unit 25 and the restored detection data d1 separated by the data separation unit 22 are identical.
If the detection data d1 and d1xe2x80x2 are judged to be identical, namely if it is judged that the source data D1 transmitted from the transceiver 10 to the receiver 20 is correct, the data comparison unit 25 outputs a first signal. In response to the first bit signal, the transceiver 10 transmits the next data D2 to the receiver 20, and the source data D1 is outputted from the data storing unit 23. Here, the first bit signal has a value of 0 or 1.
In contrast, if the detection data d1 and d1xe2x80x2 are judged not to be identical, the data comparison unit 25 outputs a second bit signal. In response to the second bit signal, the transceiver 10 does not transmit the next data D2 to the receiver 2, and the previously transmitted source data D1 is transmitted again.
In the conventional serial data transmission apparatus, only after the decoding, data separation, cyclic redundancy checking, and comparison processes are sequentially performed to determine that the data transmitted from the transceiver to the receiver is correct, the transceiver can transmit the next data to the receiver. Thus, the conventional serial data transmission apparatus has an inherent problem of lengthy transmission delay.
Accordingly, the present invention is directed to a serial data transmission apparatus that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
Another object of the present invention is to provide an improved serial data transmission apparatus which is capable of rapidly transmitting a large amount of data at a high speed by configuring a transceiver to have a function of performing an encoding operation before a cyclic redundancy checking operation is performed and by configuring a receiver to have a function of concurrently performing a decoding operation and a cyclic redundancy checking operation.
Additional features and advantages of the invention will be set forth in the description which follows and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, there is provided a serial data transmission apparatus which includes a transceiver for encoding source data D1 to be transmitted, performing a cyclic redundancy checking (CRC) operation on the encoded data D1xe2x80x2, combining a detection data d1 generated by a cyclic redundancy checking (CRC) operation and the encoded data D1xe2x80x2 generated by the encoding, and outputting a combined data (D1xe2x80x2+d1); and a receiver for separating the combined data (D1xe2x80x2+d1) received from the transceiver into the data D1xe2x80x2 and d1 which are in formats before the data D1xe2x80x2 and d1 were combined by the transceiver, concurrently performing a decoding operation of the separated data D1xe2x80x2 and a cyclic redundancy checking operation of the separated data D1xe2x80x2, comparing the separated data d1 with a detection data d1xe2x80x2 generated by the cyclic redundancy checking operation, judging whether the decoded data D1 is correct, and outputting the decoded data D1 as a received data.
In another aspect of the present invention, there is provided a serial data transmission apparatus which includes a transceiver for transmitting a source data, said transceiver having storing means for storing said source data, encoding means for encoding said source data, first checking means for checking the encoded source data to generate a first detection data, and combining means for combining said first detection data generated by said means for checking and said encoded source data to output a combined data; and a receiver for receiving said combined data.
In a further aspect of the present invention, there is provided a method, in a serial data transmission system having a transceiver with a storage means for storing a source data and a receiver, for serially transmitting said source data from said transceiver to said receiver comprising steps of encoding said source data, checking said encoded source data to generate a first detection data, combining said first detection data and said encoded source data to generate a combined data, and receiving said combined data.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.